| 秸秆覆盖与氮减施对土壤氮分布及地下水氮污染影响 |
| 摘要点击 2038 全文点击 666 投稿时间：2020-06-22 修订日期：2020-07-23 |
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| 中文关键词 秸秆 氮素 地下水 环境 河套灌区 夏玉米 |
| 英文关键词 straw nitrogen groundwater environment Hetao irrigation district summer maize |
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| 中文摘要 |
| 为探究不同秸秆覆盖方式与氮减施对土壤氮分布、地下水氮污染及夏玉米产量的影响，于2017~2018年在河套灌区开展田间试验.本试验设置常规施肥为对照（CK处理），以30%氮减施（N1）、20%氮减施（N2）和10%氮减施（N3）为3个减施水平处理，每个减施水平设秸秆表覆（B处理）和秸秆深埋（S处理）这2个处理.结果表明，CK土壤氮随土层加深呈波状分布，总体呈降低趋势；秸秆表覆的氮素在0~20 cm土层表聚，NO3--N和NH4+-N含量较CK平均提高22.2%和42.7%，随土层加深而降低；秸秆深埋的氮素在20~40 cm土层聚集，NO3--N和NH4+-N含量较CK平均提高29.8%和48.1%，随土层加深呈先增后降趋势；不同秸秆覆盖下氮素聚集量随氮减施水平提高而减小.收获后，在>80 cm土层，秸秆表覆的NO3--N和NH4+-N累积量较CK平均降低19.9%~58.2%和31.1%~61.7%，而秸秆深埋平均降低36.7%~70.9%和82.6%~89.2%，效果较秸秆表覆显著（P<0.05）；秸秆表覆仅BN3较CK平均增产0.4%，秸秆深埋SN2较CK平均增产9.3%；夏玉米产量与氮减施水平的拟合结果表明，秸秆深埋较秸秆表覆增产效果显著（P<0.05），秸秆深埋与14%~20%氮减施增产效果最优；秸秆覆盖与氮减施可缓解氮素淋溶损失，收获后秸秆深埋显著降低地下水氮污染风险（P<0.05），达到改善灌区农田生态环境和提高夏玉米产量的目的. |
| 英文摘要 |
| To explore the effects of straw mulching and reduced nitrogen fertilization on the temporal and spatial patterns of soil nitrogen, groundwater nitrogen pollution, and summer maize yield, field experiments were carried out in the Hetao irrigation district in 2017 and 2018. The experiment involved the following seven treatments:a control (CK) treatment involving conventional fertilization and traditional tillage, and conventional nitrogen applications reduced by 30% (N1), 20% (N2), and 10% (N3) coupled with either straw surface covering (B) or deep straw burial (S). The results showed that the distribution of soil nitrogen in the CK treatment varied depending on soil depth, with an overall decreasing trend. In the 0-20 cm soil layer under straw surface covering (B) treatments, soil nitrogen was superficially accumulated. NO3--N and NH4+-N content increased by an average of 22.2% and 42.7% compared to the CK treatment, respectively, which decreased significantly at first and then increased slightly with depth. In the 20-40 cm deep soil layer under the deep straw burial (S) treatments, soil nitrogen accumulated and the content of NO3--N and NH4+-N increased by an average of 29.8% and 48.1%, respectively, compared to the CK treatment. Nitrogen accumulation first and then decreased significantly with depth. Nitrogen accumulation under the different straw mulching regimes increased with an increase in the application of reduced nitrogen. After the harvest of summer maize, the accumulation of NO3--N and NH4+-N in the >80 cm soil layer under the B treatments was 19.9%-58.2% and 31.1%-61.7% lower than that of the CK treatment, respectively. This compared to reductions of 36.7%-70.9% and 82.6%-89.2% for the S treatments, respectively. Only the BN3 treatment increased accumulation compared with CK by 0.4% on average, while the SN2 treatment resulted in a 9.3% increase. Summer maize yield and relative indexes were also improved relative to the other treatments. Nonlinear fitting of yield and application reduction showed that deep straw burial was better than surface covering at increasing summer maize production. The effect of deep straw burial and 14%-20% application reduction was better. Straw mulching with reduced nitrogen fertilization can limit nitrogen leaching and thereby reduce the risk of groundwater pollution. After the harvest, groundwater quality was classified in the Ⅱ class, with the risk of nitrogen contamination being lowest under deep straw burial with>20% reduced nitrogen fertilization. These observations show that deep straw deep alongside 14%-20% application reduction could effectively alleviate nitrogen leaching and reduce the risk of nitrogen pollution in groundwater. This approach can help improve the ecological environment and summer maize yields in the Hetao irrigation district. |
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